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I added that a heavier rider doesn't necessarily wear chains faster though, and that it's really about how much power is applied to the pedals. Some light riders put down more power than heavy ones and they will wear out chains quicker.
That isn't what you said:

A skinny xc guy putting out 300 watts will probably wear out their drivetrain just as fast as a big person producing the same power.
I'm not the one who's confused.
 
Mr.Pig I really don't want to argue but those 2 quotes say exactly the same thing.
What you originally said was that two riders of different weights will wear out the transmission at the same rate if they produce the same power.

A skinny xc guy putting out 300 watts will probably wear out their drivetrain just as fast as a big person producing the same power.
What I'm saying is that this idea is bollocks. More strain will be put on the transmission to move a greater weight. Just as more strain will be put on the brakes to stop it again.
 
What you originally said was that two riders of different weights will wear out the transmission at the same rate if they produce the same power.
Which is exactly what this says-

I added that a heavier rider doesn't necessarily wear chains faster though, and that it's really about how much power is applied to the pedals. Some light riders put down more power than heavy ones and they will wear out chains quicker. With drivetrain parts it's watts, not weight.
We just disagree, the heavy rider producing the same watts as a light one will just be going slower. Strain on the drivetrain should be the same.

I guess I could be wrong but I don't think so.
 
Which is exactly what this says-

We just disagree, the heavy rider producing the same watts as a light one will just be going slower. Strain on the drivetrain should be the same.

I guess I could be wrong but I don't think so.
You aren't wrong.

The only inputs to a pedal, crankarm, chain ring, chain and cassette are torque and cadence.

Weight is not a variable in power, other than the general*** association of larger riders with more power.

***Which, of course, is not always true.
 
Yes, he is. It doesn't matter how big the engine is, a rope halling a 5kg load up a hill will be under a lot less strain than the same chain dragging up 50! How fast it goes and how long it takes are largly moot. Mr Gravity and Mr Mass are going to fight it out regardless.
You are ignoring a crucial component in your analogy.

I'll let you figure it out.
 
Real, true life story: I weigh ~250lbs. My wife weighs ~130. We ride together 95% of the time. We are usually keep pace with one another and are never out-of-sight should one of us get ahead.

In 1 year, I will go through 1 drive train and 2 additional chains (so 3 chains total). The additional chains are either due to breaking or replacement prior to being stretched too far for use. She will go through 1 chain and her drive trail usually will last 3 yrs. Last year we rode around 3800mi off-road.

Regarding the wattage discussion, I'd love to get a powertap and measure this. For me, flats give me troubles than climbs. My leg speed naturally gravitates to a slower/lower cadence.
 
I don't understand why this is even being debated. It's not remotely complicated and the notion that the two different weight riders with the same power output will cause the same wear is one of the dumbest things I've read. I feel stupider for even arguing about it!

Take two identical cars. Fill one with bricks! Except for the bit the driver sits in, yeah I'm guessing I do have to state the bleeding obvious here. Every working part of the heavier car will wear out quicker because it is having to work harder and will have more strain on it. The transmission is under greater load, the brakes have to work harder, the whole car is going to fall to bits much quicker. If you can't understand that I can't help you.
Hang on:

Take the brick loaded car and drive it 300 miles at 35MPH. Now take the identical unloaded car and mash the pedal to the floor until you hit 90MPH; then slam on the brakes. Continue doing that for 300 miles.

There are other factors at play.
 
You aren't wrong.

The only inputs to a pedal, crankarm, chain ring, chain and cassette are torque and cadence.

Weight is not a variable in power, other than the general*** association of larger riders with more power.

***Which, of course, is not always true.
Agreed, BUT:

JB's argument hinges on one key unit of measurement, TIME. For time, JB's argument holds, as the heavier rider will not have ridden as far (assuming some uphill). Some measure wear based on distance, not time. To complete a course at the same wattage it will take the heavier rider longer. A longer time at the same power will cause more wear...all other things equal.

JB's first post in this thread is correct also.
Yes, a heavier rider has to produce more power than a lighter rider to go the same speed, especially when climbing hills. More power to the pedals equals faster drivetrain wear.
At the same speed the course will be completed in the same time, thus the heavier rider will be applying more power (and likely more force) which will impart more wear on components.
 
... a 5kg load up a hill will be under a lot less strain than the same chain dragging up 50! How fast it goes and how long it takes are largly moot. Mr Gravity and Mr Mass are going to fight it out regardless.
Given the engineering definition of "strain" that is correct, but putting tension in a chain does not in and of itself result in wear. To get wear one needs some force, friction, differential movement AND time.
 
Come on people. Physics class, really? It doesn’t take a rocket scientist to know that more weight is going to wear out anything mechanical faster than less weight.



/thread
 
I'd say weight is more of an issue than height, but a rider's power output, gear ratio choice, and rider terrain preference may also contribute. At 5'10" and 165lbs, I go through chains and cassettes somewhat faster than a friend who is 5'6" and 225lbs because I climb more elevation than he does and I stand and grind in high gears while he sits and spins in lower gears.

In addition to the drivetrain wear mentioned above, heavier riders will also wear brake pads faster.
five six and two twenty five?

what is this person, a pro running back or hopelessly overweight?
 
To add:

I think the general consensus is that if you weigh > 180#, you need to ride smooth or beef up your rig. 180# seems to be the threshold at which more parts break, independent of power output. YMMV

Much like tandem stuff and clyde stuff is comparable, the 180-220# crowd probably all have enduro-level parts for riding aggressive XC. I don't know what you do for a clyde tandem. I think you end up with moto parts to keep from breaking stuff.

-F
 
You have asked a very complicated question. Shaq broke a seat post by sitting on it in a bicycle shop. As a rule of thumb if some thing works for you and you make it twice as strong it will last forever. By the same rule if some thing works for you and some one twice as strong tries to use it they might break it right away. This come from fatigue curves you can find in any engineering book. Most every one can double their strength with a little training. My leg strength doubled in a single year when I learned to ride a unicycle at the age of 10. The second problem is one of leverage. A taller person has more leverage on some parts. This can generally be ignored for questions of strength but not stiffness. A 21 inch frame is twice as stiff as a 25 inch frame. Very few manufactures take this into account when building frames. This is why Clydesdales have their own forum.
 
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